There is strong clinical evidence that excessive and abnormal movement between vertebrae accelerates the degenerative process in the human lumbar spine. This in turn can lead to painful low back pain symptoms. We have used biplanar radiography of patients to confirm this association. Animal models are required to obtain evidence of cause and effect. The proposed study will investigate the short- and long-term effects on the rabbit lumbar intervertebral joint of a mechanical instability produced surgically. This intervention has been found previously to produce degenerative change. Gross changes, change in mechanical properties and alteration in biochemical constituents of disc tissue will be studied. This will be done immediately post-operatively, and over a period of a year following surgery. The aim of the study is to use a model of mechanically induced degeneration in the rabbit spine with surgical variations in post-operative animal care to investigate the relationship between type and magnitude of mechanical instability and the rate of the degenerative change. It has been hypothesized that abnormal stress below a certain level promotes a remodelling and repair process, and above this level it leads to degenerative change. This is a minimally research area in the spine, with profound implications for our understanding of the degenerative process in the human skeleton, and ultimately the prevention of the associated painful symptoms.